Golf balls generally comprise either a one-piece construction or several layers including an outer cover surrounding a core. Typically, one or more layers of paint and/or clear coat are applied to the outer surface of the golf ball. For example, in one typical design, the outer surface of the golf ball is first painted with at least one clear or pigmented basecoat primer followed by at least one application of a clear topcoat. The clear topcoat may serve a variety of functions, such as protecting the cover material, improving aerodynamics of ball flight, preventing yellowing, and/or improving aesthetics of the ball.
One common topcoat utilizes a solvent borne two-component polyurethane, which is applied to the exterior of a golf ball. This topcoat formulation generally requires the use of a solvent that is a significant source of volatile organic compounds (VOC), which pose environmental and health concerns. Another type of coating, ultraviolet (UV) curable coatings, generally do not require solvents.
Compressed air is normally used to deliver and spray the coating materials. These techniques are prone to produce non-uniform and/or unduly thick coatings, and also fill in the dimples, which may adversely impact aerodynamic (flight) characteristics of the golf ball. In the case of UV coatings, oxygen present in air may interfere with the transmission of UV energy to the reactants, and also is prone to react with the reactants, especially the photoinitiator, thus requiring that excess quantities of reactants be used.